O₂ content in atmospheric air on volume basis is
21 %
23 %
30 %
40 %
Correct Answer :
A. 21 %
Related Questions
In case of condensing steam engines, the pressure of steam in the cylinder during exhaust stroke is _________ the atmospheric pressure.
Equal to
Lower than
Higher than
None of these
The expansion of steam, as it flows over the blades in reaction turbine, represents
Isothermal process
Isentropic process
Throttling process
Free expansion process
The amount of water evaporated in kg per kg of fuel burnt is called
Evaporative capacity of a boiler
Equivalent evaporation from and at 100° C
Boiler efficiency
None of these
Expansion ratio is the ratio of
Swept volume to the volume at cut-off
Clearance volume to the swept volume
Volume at cut-off to the swept volume
Swept volume to the clearance volume
In an ideal impulse turbine, the
Absolute velocity at the inlet of moving blade is equal to that at the outlet
Relative velocity at the inlet of the moving blade is equal to that at the outlet
Axial velocity at inlet is equal to that at the outlet
Whirl velocity at inlet is equal to that at the outlet
Fire tube boilers are limited to a maximum design working pressure of
1 kg/cm
6 kg/cm
17 kg/cm²
100 kg/cm²
The mechanical draught _________ with the amount of smoke.
Increases
Decreases
Does not effect
None of these
Which of the following is a fire tube boiler?
Locomotive boiler
Babcock and Wilcox boiler
Stirling boiler
All of the above
The draught in locomotive boilers is produced by a
Chimney
Centrifugal fan
Steam jet
None of these
In a nozzle, whole frictional loss is assumed to occur between
Inlet and throat
Inlet and outlet
Throat and exit
All of these
The heat balance sheet for the boiler shows the
Complete account of heat supplied by 1 kg of dry fuel and the heat consumed
Moisture present in the fuel
Steam formed by combustion of hydrogen per kg of fuel
All of the above
The temperature of flue gases at air heater outlet should be
100°C
Above dew point temperature of flue gases
Below dew point temperature of flue gases
Less than wet bulb temperature of flue gases
The dry saturated steam at very low pressure, (510 kg/cm²) when throttled to atmosphere will become
Wet
Superheated
Remain dry saturated
Dry
The diameter of tubes for natural circulation boiler as compared to controlled circulation boilers is
More
Less
Same
Could be more or less depending on other factors
The increase in pressure
Lowers the boiling point of a liquid
Raises the boiling point of a liquid
Does not affects the boiling point of a liquid
Reduces its volume
When the total heat of steam is h kJ/kg and the sensible heat of feed water is hf1 kJ/kg, then the factor of evaporation is given by
(h - hf1)/2257
(h + hf1)/2257
(h × hf1)/2257
None of these
Lancashire boiler has __________ internal flue tubes.
One
Two
Three
Four
Lancashire boiler is a
Stationary fire tube boiler
Stationary water tube boiler
Water tube boiler with natural/forced circulation
Mobile fire tube boiler
In a throttling process
Steam temperature remains constant
Steam pressure remains constant
Steam enthalpy remains constant
Steam entropy remains constant
An economiser is generally placed between
Last superheater or reheater and air preheater
Induced draft fan and forced draft fan
Air preheater and chimney
None of the above
Hard coke is used in
Cement industry
Thermal power plant
Blast furnace
Domestic use
100% efficiency of a thermal cycle cannot be achieved because of
Frictional losses
It is not possible to achieve 0°K temperature
Leakage
Non availability of ideal substance
The steam temperature with increase in load in case of a boiler fitted with radiation superheater
Increases
Decreases
Remain unaffected
First increases and then decreases
In a Woolf type compound engine, the high pressure and low pressure cylinders
Have common piston rod
Are set at 90°
Have separate piston rod
Are set in V-arrangement
Carbonisation of coal is the process of
Pulverising coal in inert atmosphere
Heating wood in a limited supply of air at temperatures below 300°C
Strongly heating coal continuously for about 48 hours in the absence of air in a closed vessel
Binding the pulverised coal into briquettes
For the same diameter and thickness of tube, a water tube boiler compared to a fire tube boiler has
More heating surface
Less heating surface
Equal heating surface
Heating surface depends on other parameters
The capacity of induced draft fan compared to forced draft fan in a boiler is
Same
More
Less
Less or more depending on size of boiler
A single acting steam engine produces ________ power than that of double acting steam engine.
Equal
Half
Double
Four times
When the circulation of water, in a boiler, is by a centrifugal pump, then the boiler is known as
Internally fired boiler
Externally fired boiler
Natural circulation boiler
Forced circulation boiler
The length of Cornish boiler varies from
2 to 4.5 m
3 to 5 m
5 to 7.5 m
7 to 9 m